Page 12 of 13 FirstFirst ... 210111213 LastLast
Results 111 to 120 of 130

Thread: 3 EASY ANTENNAS FOR BEGINNERS

  1. #111
    Flight attendant
    Join Date
    Mar 2016
    Posts
    82
    Has anyone got the dimensions of the Flightaware 1090MHz filter?
    Could it be, that its metal can has intrinsically the correct dimension to work as a cantenna?
    so the easiest way would have been just to stick a 68mm long piece of wire in its input and to wind 4 loops of cable at the other side to build a balun?

  2. #112
    Flight attendant
    Join Date
    Mar 2016
    Posts
    82
    Quote Originally Posted by abcd567 View Post
    The trickiest thing in J-pole, Slim Jim and Franklin dipole with matching stub is the accurate placement of cable tap off on the stub. At Ghz frequencies, few mm away from optimum point, and the antenna transforms from "very good" to "poor".
    I made another antenna deliberately placing the tap point 12 mm from the bottom:
    DUMP1090-Antenna2.jpg

    That one worked also pretty well, maybe the right point is around 9mm?
    Anyhow these antennas are really easy to build and perform much better than the shortened stock whip.

  3. #113
    Captain abcd567's Avatar
    Join Date
    Sep 2013
    Location
    Toronto CYYZ
    Posts
    2,862
    Quote Originally Posted by RIN67630 View Post
    Has anyone got the dimensions of the Flightaware 1090MHz filter?
    Could it be, that its metal can has intrinsically the correct dimension to work as a cantenna?
    so the easiest way would have been just to stick a 68mm long piece of wire in its input and to wind 4 loops of cable at the other side to build a balun?
    This is not going to work. The basic requirement of a coaxial antenna (and it's wide-bodied varient Cantenna), is that the sleeve is connected to ground at top, but isolated from ground at bottom. The cylinderical metallic housing of Flightaware Filter is connected to ground both at top & bottom. Please see the drawing below.

    Please note that the coaxial antenna at right, although an old design, was not very popular as it did not have as good performance as other dipole designs. I realized that the narrow dia of copper pipe/tube has resulted in very narrow air gap between coax and tube, and this was the main reason of its poor performance. I then decided to use a much larger dia sleeve to enlarge the air gap, and this proved successful, and was birth of the Cantenna. I did try narrow dia sleeve made of 3/4 inch (20 mm) dia copper pipe, another with medium dia (54mm) drink can, and third with wide dia (68mm) Pepsi can. The 68mm dia can proved best, and 20mm dia pipe proved worst.

    (English translation in red added by me)

    Last edited by abcd567; 2016-03-29 at 23:25.

  4. #114
    Captain abcd567's Avatar
    Join Date
    Sep 2013
    Location
    Toronto CYYZ
    Posts
    2,862
    Last edited by abcd567; 2016-03-31 at 20:25.

  5. #115
    First officer
    Join Date
    Sep 2013
    Location
    Farnborough, UK
    Posts
    204
    careful this is turning into a not so easy antenna thread.
    T-EGLF8

  6. #116
    Flight attendant
    Join Date
    Mar 2016
    Posts
    82
    Quote Originally Posted by SpaxmoidJAm View Post
    careful this is turning into a not so easy antenna thread.
    My words. The Jpole is the easiest. It fits in a piece of 16mm PVC tube.
    Forget amplifiers, forget expensive coax cables and connectors, adapters etc...

    The trick is to use the short stock cable and place receiver and Pi close to the antenna.

    I get ~280nM every day and my current antenna location is far from being perfect, it is still not above the roofes around.

    T-EDLW40 Statistics (from an average day):
    STATUS: Online CURRENT UPLOAD RATE: 0 KB/S FIRST SEEN ONLINE: 2016-01-03 22:59:14
    LOCAL IP: N/A MAC ADDRESS: 00:00:00:00:00 COORDINATES: 51.3684,7.9404
    UPTIME (AS % OF AVAILABLE TIME): 100% AIRCRAFT SEEN: 1,788 POSITIONS REPORTED: 84,496
    MAXIMUM DISTANCE: 286nm
    Last edited by RIN67630; 2016-04-02 at 03:01.

  7. #117
    Captain abcd567's Avatar
    Join Date
    Sep 2013
    Location
    Toronto CYYZ
    Posts
    2,862
    @RIN67630:
    Your statistics with J Pole antenna are great, congratulations!
    What were your statistics with 1/4 λ groundplane antenna?

    A comparison of two statistic will quantitatively highlight the difference of J Pole and 1/4 λ groundplane antennas.

  8. #118
    Passenger
    Join Date
    Apr 2018
    Location
    Łdź, PL
    Posts
    4
    Hi there!
    Is power inserter the same as power/voltage separator as I can't find "power inserter" analogue here in Poland.
    9e7061014cd8b3e0c0b0bb1ccfd1.jpeg
    ww.JPEG
    or something like this:
    ww2.JPEG

    thanks for help!

  9. #119
    Captain abcd567's Avatar
    Join Date
    Sep 2013
    Location
    Toronto CYYZ
    Posts
    2,862
    Quote Originally Posted by Faddah View Post
    Hi there!
    Is power inserter the same as power/voltage separator as I can't find "power inserter" analogue here in Poland.
    Yes, it is same.
    This one (ASZ-03R) is OK if you want to use one receiver (DVB-T) with one antenna
    9e7061014cd8b3e0c0b0bb1ccfd1.jpeg
    ww.JPEG

    This one (ASZ-04/2) is OK if you want to use two receivers (DVB-T) with one antenna. If you connect two receivers (DVB-T), the signal will be divided between the two, and each will get half the strength.
    ww2.JPEG

  10. #120
    Purser
    Join Date
    Nov 2016
    Posts
    155
    Can anyone explain - in simple terms - the differences between having 3 -4 - 6 or 8 radials. I've seen examples of all these and would assume 8 is best but does this affect the operation ?

    ylis

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •